The present invention relates to a sealing assembly in a filler neck, and particularly to means for establishing a seal between the filler neck and a liquid-dispensing nozzle in the filler neck. More particularly, the present invention relates to a sealing assembly in a vehicle fuel system filler neck for sealingly admitting a fuel-dispensing nozzle into the filler neck without permitting substantial exhaustion of fuel vapors in the filler neck to the atmosphere or admission of atmospheric pressure into the fuel system through the filler neck.
Polluting emissions are released into the atmosphere during each and every motor vehicle refueling activity through the mouth of the filler neck. In view of the frequency of vehicle refueling activities, it will be appreciated that a significant quantity of otherwise combustible fuel is lost to the atmosphere each time a vehicle is refueled.
New fuel vapors are generated during refueling due to splash and agitation of the dispensed fuel, as well as from potential temperature differences between the fuel tank and the dispensed fuel. In addition, as the liquid fuel dispensed at the pump fills the vehicle fuel tank, fuel vapors that are present in the tank and generated during refueling are displaced by liquid fuel. These displaced fuel vapors are moved out of the fuel tank vapor space by the displacing action of the liquid fuel. In conventional vehicle fuel systems, these displaced vapors are released directly into the atmosphere via the fuel tank filler neck and are a contributing factor to air pollution.
Conventional filler necks and fuel tank assemblies on vehicles are not configured to control this escape of fuel vapor effectively during the refilling process. Generally, the filler neck of a vehicle has a diameter greater than the diameter of the fuel-dispensing nozzle. Because of the relatively large diameter of the filler neck with respect to the fuel-dispensing nozzle, the fuel vapor created by fuel dispensed into the fuel tank through the filler neck escapes out through the filler neck and to the atmosphere substantially continuously during the filling operation. This creation of fuel vapor during the refueling process has recently been recognized as a major contributor to pollution of the atmosphere, especially with newer, more volatile blends of vehicle fuel.
Attempts have been made to control this escape of fuel vapor during the filling process by adapting the service station fuel-dispensing nozzle to include a vapor recovery portion which captures the escaping fuel vapor and prevents the fuel vapor from escaping into the atmosphere. Such conventional methods of capturing the escaping fuel vapor have generally proven unsatisfactory because of the complexity of the system and because of relatively poor vapor-capturing characteristics of the system. It is generally recognized that for satisfactory fuel vapor control during refilling, a system must be provided which is on-board the vehicle for capturing and controlling such fuel vapor generated during refilling. Ideally, such a system would work automatically without any operator supervision.
Another problem with conventional filler neck and fuel tank assemblies is that it is sometimes extremely difficult to achieve accurate filling levels because of poorly designed filler neck seals which leak, resulting in an inability to maintain any vacuum that might develop in the filler neck itself during introduction of fuel into the filler neck. Conventional fuel nozzles are often equipped with vacuum-actuated systems that shut off flow of fuel through the nozzle upon exposure of a sensor in the nozzle to a predetermined negative pressure. Typically, the splashed back fuel enters and blocks a conduit formed in the nozzle to lie in communication with the sensor to generate the negative pressure, thereby shutting off fuel flow.
Relying upon fuel splash-back provides generally unsatisfactory fill level consistency because such fuel splash back is dependent upon a number of factors. Such factors include the flow rate of the nozzle, the configuration and routing of the filler neck, and the general orientation of the filler neck with the fuel tank, as well as fuel-dispensing nozzle sensitivity. Because of such inconsistency in achieving accurate fill levels, it would be advantageous to provide a nozzle shutoff control system having an improved means for providing a negative pressure signal to a vacuum-actuated shutoff sensor which would ideally permit the fuel tank to be filled to accurate, consistent fill levels during each refueling operation.
One object of the present invention is to provide a sealing assembly for partitioning a fuel-conducting passageway in a filler neck to limit flow of vapors and gases through the passageway during dispensing of fuel into the filler neck and past the sealing assembly.
Another object of the present invention is to provide a sealing assembly for preventing fuel vapor loss to the atmosphere through the filler neck during refueling in cooperation with a fuel vapor recovery system.
Yet another object of the present invention is to provide a sealing assembly for blocking communication of an inner chamber of the filler neck with the atmosphere during refueling to maintain a negative pressure condition in the inner chamber in cooperation with a vapor-handling system to enhance operation of a vacuum-actuated nozzle shutoff system communicating with the inner chamber.
According to the present invention, a sealing assembly is provided for use in a filler neck sized to receive a fuel-dispensing nozzle. The sealing assembly includes means for establishing a seal between the filler neck and a fuel-dispensing nozzle and means for locating the establishing means in the filler neck to define in the filler neck an outer chamber communicable with the atmosphere and an inner chamber. The establishing means is configured to admit the fuel-dispensing nozzle into the inner chamber without coupling the inner and outer chambers in vapor communication.
In preferred embodiments, the filler neck includes an inner wall defining a nozzle-receiving passageway and means coupled to the inner wall for supporting the establishing means. The supporting means provides a first sealing surface and a fuel-dispensing nozzle insertable into the nozzle-receiving passageway provides a second sealing surface. The establishing means communicates with both of the first and second sealing surfaces upon admission of a fuel-dispensing nozzle into the inner chamber through the outer chamber to define a vapor and atmosphere seal between the filler enck and the nozzle.
In one preferred embodiment, the supporting means is unitarily appended to the inner wall to prevent flow of any fuel vapor and atmosphere between the filler neck and the supporting means. The establishing means is provided by a sealing ring having an outer perimeter edge providing means for sealing against the first sealing surface on the supporting means and an inner perimeter edge defining a central nozzle-receiving aperture. The inner perimeter edge provides means for sealing against the second sealing surface on the nozzle.
One feature of the present invention is the provision in a filler neck of seal-establishing means for admitting a fuel-dispensing nozzle into an inner chamber in the filler neck without coupling the inner chamber to the atmosphere through the filler neck mouth. One advantage of such a sealing system is that it helps to prevent fuel vapor loss through the filler neck during operation of an on-board vehicle fuel vapor recovery system by blocking flow of pressurized fuel vapor in the filler neck to the atmosphere during refueling. Another advantage of this sealing system is that it cooperates with a vapor-handling system in a vehicle fuel system to maintain any negative pressure condition that develops in the inner chamber during refueling to enhance the operation of a vacuum-actuated nozzle shutoff system having its shutoff sensor communicating with the inner chamber.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.